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Re: ORP

On 23/2/97 8:38 PM, Mike Roberts wrote:
>
>Well I appreciate the responses I received about UV sterilizers and protein
>skimmers.  Here is my last question about adapting various reef 
>technologies to
>the hi-tech plant aqaurium:
>
>  What about Ozone with an ORP controller? any benefit in a heavily planted
>tank?

As the person who made a posting some time ago about how he was running a 
plant tank on principles borrowed from reef tanks, and who claimed that 
Delbeek and Sprung's "The Reef Aquarium" was a good guide for planted 
tanks, my understanding is that ozone will do 2 things - increase the 
redox potential of the water, and remove colouration from organics.

I have really clear water with no trace of colouration in my planted tank 
which runs without a filter. The plants do a wonderful job of removing a 
lot of organics on their own, and I see little reason to add ozone for 
that. It's probably cheaper and a lot easier just to toss a bag of 
activated carbon, or Purigen, into the back of the tank if needed. Julian 
Sprung recommends a bag of carbon just placed in the sump of a reef tank 
to clean up yellowing of the water from organics. I've tried this in my 
tank before it was anywhere near as planted as it now is, and when I had 
wood leaching tannins into the water, and it cleared up the water 
extremely well. You definitely don't need to place it in a filter and 
force water through it.

In relation to redox potential, I think what occurs is as follows (but 
I'm willing to be corrected).

Our fish produce wastes like ammonia, and other organic wastes also get 
into the system from the fish and from decay of plant material, dead 
fish, etc. These wastes can get removed by one of 2 means -oxidation 
processes or other processes which include plant photosynthesis.

Oxidation processes (ammonia to nitrite to nitrate for example, and 
phosphorous compounds to phosphate) consume oxygen and lower the redox 
potential. Photosynthesis produces oxygen and does not lower the redox 
potential.

Ozone also produces an oxidation process, but the breakdown of ozone (O3) 
into a free oxygen atom which drives the oxidation, and an oxygen (O2) 
molecule, adds oxygen to the system and does not reduce the redox 
potential.

In other words, the use of plants to deal with waste products reduces the 
quantum of oxidation processes occurring in the tank and thereby promotes 
an elevated redox potential. Heavy planting should therefore make the use 
of ozone redundant.

As I understand Sprung's approach to ORP and redox in reef tanks, it is 
that it can help but you're better off getting redox to acceptable levels 
through good tank management than by adding lots of technology. He also 
runs the line that what counts is how the tank inhabitants (including 
plants in our case) are going, not blind adherence to tinkering to get 
the numbers right. People can become fixated on getting the numbers right 
while the tank actually goes downhill.

I would agree with that. If the tank looks healthy, and stays healthy, 
keep with what you're doing and learn from what helps and what hinders 
your results. Keeping things simple is cheaper and means less 
maintenance. I think it's a lot more satisfying in the long run.

Where I think lots of technology becomes useful is if, for some reason, 
you _need_ to keep a higher fish load than the tank will support (eg a 
wholesaler's fish holding system), or you must work with some other 
marginal situation for some reason, and you absolutely have to rely on 
every bit of technology around to keep it going. That's not the way to go 
about enjoying your tank as a hobby - that's hard work!

David Aiken